This invention relates generally to a sealant mold for use with a domed nutplate unit or the like for sealing a lower portion of the nutplate unit particularly such as an adhesively mounted interface with a substrate against exposure to undesirable fluids and the like. More particularly, this invention relates to an improved sealant mold and related method of use wherein the lower portion of a domed nutplate unit or the like is effectively sealed with a minimum weight addition.
Domed nutplate units and the like are generally known in the art, wherein a nutplate or other selected fastener device is encased within a dome or dome element to prevent contact with fluids present on one side of the dome. The fastener device is typically mounted onto a selected substrate, such as the wall of an aircraft fuel tank or the like, wherein the dome further is intended to prevent leakage of fluid such as aircraft fuel through a substrate bolt hole or the like aligned with the nutplate. In the past, such domed nutplate units have been mounted onto the substrate by means of rivets. More recently, as described in U.S. Pat. Nos. 5,013,791 and 5,304,747 (which are incorporated by reference herein), adhesive mounting techniques for mounting the domed nutplate onto the substrate have been developed.
In an aircraft fuel tank environment, it can be highly desirable to seal the attachment interface between a domed nutplate unit and a substrate. In a rivet-mounted nutplate unit, such sealing can be critical in preventing undesirable fuel leakage to the exterior of a fuel tank. In an adhesively mounted nutplate unit, sealing can be important to prevent undesirable degradation of the attachment material. In either case, it is highly desirable to provide a sealant material in a sufficient thickness and to apply this sealant material with great care to preclude any pinholes or voids that might otherwise allow fuel and/or water within the aircraft fuel tank to leak past the sealant and cause rivet corrosion and/or attack the adhesive material. However, in a modern aircraft environment, it is also important to note that additional weight added to the aircraft for use in sealing the attachment interface can be undesirable for its negative impact on overall fuel efficiency.
In the past, various mold devices have been proposed and used for applying sealant material over a domed nutplate unit or the like, wherein this sealant material cures to a relatively tough and rubbery state that is substantially impervious to attack or contamination due to contact with fuel and/or water within the aircraft fuel tank. However, the existing mold devices generally apply an excess amount of sealant material to cover substantially the entire nutplate unit within the fuel tank, and these mold devices are not adapted for convenient removal following curing of the sealant material. Accordingly, the excess amount of sealant material in combination with the non-removable mold devices contributes to undesired weight addition to the aircraft.
The present invention overcomes these problems and disadvantages by provided an improved sealant mold designed to apply a curable sealant material only to a portion of a domed nutplate unit or the like at a location surrounding the attachment interface thereof with a substrate such as a wall of an aircraft fuel tank or the like, and further wherein the improved sealant mold is removable quickly and easily following curing of the sealant material.